| Insoft Limited | Administrative & support | 2006 |
| Inspire Home Decor Ltd | Wholesale & retail | 2022 |
| Inspire Shape Build Group Holdings Ltd | Financial services | 2025 |
| Inspire to Wellbeing Limited | Health & social care | 2017 |
| Inspired by D Limited | Other services | 2022 |
| Inspired Clinical Solutions Ltd | Professional & scientific | 2024 |
| Inspired Solutions UK Limited | Information & communication | 2004 |
| Inspiricare Ltd | Health & social care | 2016 |
| Inspiricare OH Limited | Health & social care | 2019 |
| Inspiricare PC Limited | Health & social care | 2010 |
| Inspiring Educators Limited | Administrative & support | 2026 |
| Install Zinc Ltd | Construction | 2015 |
| Instant Global Services Limited | Wholesale & retail | 2016 |
| Instant Heating Services Ltd | Construction | 2017 |
| Instant International Freight UK Limited | Transport & logistics | 2019 |
| Instant Solutions PTY Ltd | Information & communication | 2008 |
| Instantmart Limited | Wholesale & retail | 2026 |
| Instinct Anatomy Life Ltd | Education | 2021 |
| Instruct Design Build Ltd | Professional & scientific | 2022 |
| Instyora Private Limited | Wholesale & retail | 2026 |
| Insurearch Tech Ltd | Information & communication | 2016 |
| Integral Media Strategies Ltd | Professional & scientific | 2011 |
| Integral Physiotherapy Services Limited | Other services | 2025 |
| Integrated Logistics Solutions Limited | Information & communication | 2018 |
| Integrated Modular Solutions Limited | Construction | 2017 |
| Integrated Surgical Services LLP | | 2024 |
| Integrated Therapy Assistant Academy (Itaa) Ltd | Education | 2025 |
| Integration of Women Across Cultures CIC | Professional & scientific | 2025 |
| Integritude Solutions Ltd | Information & communication | 2023 |
| Integrity Investments Ltd. | Wholesale & retail | 2021 |
| INTEGRITY36 Consultancy Limited | Information & communication | 2023 |
| Intelecision Limited | Information & communication | 2013 |
| Intellecto Ltd | Real estate | 2024 |
| Intellectyx Limited | Information & communication | 2025 |
| Intelligent Automation Ltd | Wholesale & retail | 2009 |
| Intelligent Care Software Limited | Information & communication | 2017 |
| Intelligent Commercial Performance Limited | Professional & scientific | 2017 |
| Intelligent Medicine Ltd | Health & social care | 2008 |
| Intelligent Risk Solutions Limited | Administrative & support | 2006 |
| Intelligent Security Defender Ltd | Administrative & support | 2021 |
| Intelligent Spaces AV (UK) Limited | Other services | 2017 |
| Intelligent Workplace Solutions Ltd | Administrative & support | 1999 |
| Intelligo Consulting Ltd | Professional & scientific | 2015 |
| Intellimed Holdings II Ltd | Real estate | 2025 |
| Intellimed Holdings Ltd | Real estate | 2021 |
| Intellipharm Limited | Professional & scientific | 2008 |
| Intensity Barkingside Ltd | Wholesale & retail | 2026 |
| Intensity Chigwell Limited | Wholesale & retail | 2025 |
| Intensity Ilford Limited | Wholesale & retail | 2023 |
| Intensity Peterborough Limited | Wholesale & retail | 2016 |
| Intensity Properties Ltd | Real estate | 2019 |
| Intensity Southminster Ltd | Wholesale & retail | 2025 |
| Intensity Stanford Ltd | Wholesale & retail | 2022 |
| Inter Continental Solutions Ltd | Other services | 2020 |
| Inter Ocean Lines Limited | Transport & logistics | 2019 |
| Inter-Consulting Europe ( UK ) Ltd | Information & communication | 2003 |
| Inter-Consulting Europe Ltd | Information & communication | 2006 |
| Interactive House Ltd | Information & communication | 2009 |
| Interband Ltd | Manufacturing | 2026 |
| Intercentive Limited | Other services | 2000 |
| Interconnect.Co.Uk Limited | Professional & scientific | 2000 |
| Interfaz System Consultants Limited | Information & communication | 1997 |
| Intergalactic Systems Ltd | Information & communication | 2018 |
| Interieur London Limited | Professional & scientific | 2013 |
| Interior Design Procurement Limited | Professional & scientific | 2022 |
| Interior Dorcat Ltd | Construction | 2021 |
| Interior Soul Ltd | Construction | 2016 |
| Interiors by Isha Limited | Professional & scientific | 2021 |
| Interiorstwelve Limited | Arts & recreation | 2016 |
| Interlink Business Systems Ltd. | Information & communication | 2003 |
| Interlink International Trading (UK) Limited | Other services | 1994 |
| Interlnkd Consultancy Ltd | Professional & scientific | 2021 |
| Interlnkd Limited | Information & communication | 2021 |
| Interlock Paving Business Limited | Construction | 2016 |
| International Achiever Book of World Records Limited | Information & communication | 2025 |
| International Book of Honour Ltd | Information & communication | 2021 |
| International Centre for Prevention and Prosecution of Genocide (Icppg) | Professional & scientific | 2018 |
| International Centre of Justice for Palestinians | Other services | 2020 |
| International Charter Limited | Information & communication | 2002 |
| International Compliance Solutions Limited | Professional & scientific | 2013 |
| International Development European Company Limited | Professional & scientific | 1995 |
| International Flight Training Academy Ltd | Education | 2025 |
| International Football Management Limited | Financial services | 2025 |
| International Freight Services Limited | Transport & logistics | 1967 |
| International Investment and Capacity Enhancement Group Limited | Construction | 2020 |
| International Items Limited | Wholesale & retail | 2025 |
| International Laar Business UK Ltd | Administrative & support | 2021 |
| International Logistic Services Limited | Administrative & support | 2017 |
| International Management Services Limited | Other services | 1979 |
| International Performing Rights Limited | Arts & recreation | 2012 |
| International School of Learning Ltd | Administrative & support | 2014 |
| International Wholesalers Limited | Wholesale & retail | 2024 |
| International Yachting Professional Training Ltd | Transport & logistics | 2024 |
| Interoil Group Limited | Professional & scientific | 2012 |
| Intertop Limited | Wholesale & retail | 1994 |
| Intevia Healthcare Ltd | Administrative & support | 2025 |
| Intisar Consulting Limited | Information & communication | 2018 |
| Into the Aether Ltd | Health & social care | 2025 |
| Intoto Limited | Wholesale & retail | 2025 |
| Intouch Security Solutions Limited | Administrative & support | 2010 |